On 15th October I wrote about the connection between B vitamins and healthy bones and I also mentioned how elevated homocysteine levels may be implicated in bone deterioration and heart disease.  Today I want to look at the link between elevated homocysteine levels, low vitamin B12 levels and cognitive (mental) decline.

To recap: Homocysteine is produced when the amino acid (the building blocks of protein) methionine is broken down in the body.  Normal levels of homocysteine are important to help build and maintain body tissues, however elevated concentrations in the blood can be harmful and have been associated with an increased risk of many disorders.  At normal levels homocystein can be converted in the body into a harmless substance called cystanthionine.  The conversion of homocysteine into this harmless substance depends upon various B vitamins  (B6, B12 and folic acid).  Having good levels of these B vitamins appears to be a very good way of preventing high homocysteine levels and low levels of B vitamins have been associated with raised homocysteine levels.

A new study (1) was recently published which showed that older adults who have vitamin B12 levels that are low, but still within the normal range, may exhibit a quicker rate of brain shrinkage (brain volume loss) as they age compared to those who have good levels.  The authors wanted to investigate the association between vitamin B12 status and brain volume loss in a population of adults aged 61-87 over a 5 year period.  The participants were free of cognitive impairment (they were free of dementia) at the start of the study.  Those with lower vitamin B12 levels at the start of the study experienced the greatest decrease in brain volume over the 5 year period.  This was only a small preliminary study involving 107 individuals, the authors suggest that low vitamin B12 status should be further investigated and that trials with vitamin B supplements would be useful.

A loss in brain volume has been linked to a faster rate of mental decline and progression to diseases such as Alzheimer’s disease and dementia.  Vitamin B12 is extremely important in order to keep nerve cells healthy.  The study mentioned above (1) suggests, but does not prove, that modifying vitamin B12 status could be important in protecting the brain and preventing cognitive decline.  The results of the study do suggest that it is important to keep our vitamin B12 levels higher than just the minimum.

A study last year (2) looked at the association between cognitive decline and vitamin B12.  The study included 1684 individuals who were followed for 10 years.  Mental state (cognition) was examined a minimum of 3 times over the 10 years as were serum vitamin B12 concentrations.  Analysis of the results found that reduced vitamin B12 status was associated to cognitive decline.  The investigators also found that a high homocysteine level was associated with a greater rate of cognitive decline.  Again the authors indicate the need for further studies and supplementation trials for the prevention of dementia.

A review (3) paper published this year discussed the importance of vitamin B12 for brain health throughout life from infancy to adulthood.  In childhood low vitamin B12 levels may be related to behavioural problems and in adults it seems to be related to social development, depression and cognitive problems.  It seems as though this nutrient really is vital throughout our lifespan. 

Many older adults in the UK have lowered vitamin B12 levels.  In the diet, B12 comes from meat, fish, dairy, other animal products, and fortified breakfast cereals. Strict vegetarians, who avoid meat, and vegans, who avoid all animal products, are also at risk of B12 deficiency.  Studies seem to suggest that anything in the stomach that affects the normal acidity and digestive processes, ranging from infections to acid reflux medications to aging, may also interfere with the absorption of vitamin B12. 

The vitamin B group work very well as a team and interact in many processess, if you decide to take a supplement it may well be worth considering a multi-B vitamin supplement rather than single B vitamin supplement, or a broad spectrum multi-nutrient supplement (I prefer food state supplements which appear to be more easily absorbed by the body).

(1) Vogiatzoglou A et al.  2008.  Vitamin B12 status and rate of brain volume loss in community-dwelling elderly.  Neurology.  71:826-832
(2)Clarke R et al.  2007.  Low vitamin B-12 status and risk of cognitive decline in older adults.  Am J Clin Nutr.  86:1384-1391
(3)Black MM.  2008.  Effects of vitamin B12 and folate deficiency on brain development in children.  Food Nutr Bull.  29:S126-131

Written by Ani Kowal